Explosive materials have a wide variety of applications. Primary explosives are sensitive explosive materials that are used, in relatively small quantities, to initiate a secondary or main explosive charge. Primary explosives should be sufficiently sensitive to be detonated reliably but not so sensitive as to be exceedingly dangerous to handle. Moreover, primary explosives should have sufficient thermal stability so as to not decompose on extended storage or temperature fluctuation. Many primary explosives in current use contain lead, with the most well-known example being lead azide. These lead-containing explosives are undesirable from an environmental standpoint, since their use and manufacture can contribute to or cause lead contamination.
Thus, there is a need in the art for lead-free explosive materials and in particular for lead-free primary explosives. Certain lead-free primary explosives have been proposed. For instance, nitrotetrazole-based primary explosives have been proposed in U.S. Pat. Nos. 4,093,623 and 4,094,879, as well as in U.S. Patent App. Pub. No. 2006/0030715. For a variety of reasons, some of these proposed compounds have failed to serve as commercially viable substitutes for lead-containing primary explosives, while others exhibit characteristics that make them undesirable for at least some commercial applications. For example, U.S. Patent App. Pub. No. 2006/0030715 discloses certain nitrotetrazole complexes (including copper(II) complexes) which form a crystalline structure that is difficult to work with from a handling and ordinance loading standpoint.